When breaking young two-year old colts and fillies to a jog cart for training and racing purposes, it is necessary to have one man walk along each side of the horse, to the rear thereof, with lead lines extending to the head of the horse. These lead lines, known as the third and fourth lines, are in addition to the first and second lines which are controlled by the trainer seated on the regulation seat on the jog cart.
The purpose of the third and fourth lineman is to keep the young horse from rearing up into the air which could in turn result in a rearward falling of the horse, doing damage to himself, the jog cart, and possibly the trainer. By using the third and fourth lineman, the trainer has complete control of the horse at all times. Normally, after a few days, one man and a line can be eliminated with the second man and line being required for from two days to two weeks, depending upon the progress of the particular horse.
During that portion of the training involving the use of one or both of the lineman, the men will frequently have to sprint to keep up with the horse. At those times when the horse is moving too fast for the men to keep up with on foot, it is normal practice for the men to jump up and sit on the shafts of the cart to each side of the trainer. The third and fourth lines are long enough to reach from the horse's bit to the rear of the jog cart, thus causing no difficulty in this regard.
This ride on the shaft of the jog cart can last anywhere from 20 yards to 100 yards or more before the horse starts to act up and the men have to jump off to control the horse. This action is repeated many times during the training of the horse.
In addition to the obvious danger involved in jumping onto and off of the shaft, the shaft section that the lineman sit on is, of necessity, directly over the wheels. This in turn is very uncomfortable and presents a substantial danger in view of the frequency tendency for the feet, and particularly the heels, of the men engaging against or actually getting caught within the rapidly rotating wheel spokes. Not only can this cause injury to the men themselves, but, because of the noise produced, the horse will frequently be spooked.
Infofar as is known, the only means for avoiding the discomfort and danger associated with sitting on the shaft of the bike is the less-than-satisfactory use of a flat board wired to the shaft and covered with padding. This solution makes no provision for protecting the feet of the linemen or the wheel of the cart. By the same token, the proper mounting and removal of the board is difficult and time-consuming.